1. Technical Field
This invention relates to data processing systems. In particular, this invention relates to a data security system using on-chip secure key storage, which is particularly suitable for use in portable data processing devices.
2. Description of Related Art
The use of portable data processing systems has increased significantly in recent years. In addition to so called “laptop” and “tablet” computers, there is a growing popularity in handheld data processing devices, often called a “personal digital assistant” or “PDA.” All of these devices are capable of storing a significant amount of user data, including calendar, address book, tasks and numerous other types of data for business and personal use. Most handheld data processing devices have the ability to connect to a personal computer for data exchange, and many are equipped for wireless communications using, for example, conventional email messaging systems. Depending upon the user's needs much of this data can be highly sensitive in nature, especially for example in a government, military or commercial context.
Portable data processing systems are typically password protected, which is sufficient to protect the information against attack by ordinary individuals. However, if the device were to fall into the hands of a technically sophisticated individual with malicious intent, there are ways to obtain the data stored in memory in such a device. For example, if the data is not encrypted, a technically skilled individual can remove the memory chip and extract the data directly from the chip.
If the data is encrypted, it can only be compromised if the attacker has access to the encryption key. In a software-based encryption system, the encryption key is accessible to a technically sophisticated individual who has unlimited access to the device. Furthermore, software-based encryption systems are often cumbersome, and as such degrade processing speed and overall system performance.
It is accordingly desirable to provide a hardware-based encryption system that encrypts and decrypts data in real time, without markedly reducing the operating speed of the device or markedly increasing energy consumption.